/*
 * Copyright (C) 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#ifndef WTF_HashTraits_h
#define WTF_HashTraits_h

#include <wtf/Assertions.h>
#include <wtf/HashFunctions.h>
#include <utility>
#include <limits>

namespace WTF
{

using std::pair;
using std::make_pair;

template<typename T> struct IsInteger           {
    static const bool value = false;
};
template<> struct IsInteger<bool>               {
    static const bool value = true;
};
template<> struct IsInteger<char>               {
    static const bool value = true;
};
template<> struct IsInteger<signed char>        {
    static const bool value = true;
};
template<> struct IsInteger<unsigned char>      {
    static const bool value = true;
};
template<> struct IsInteger<short>              {
    static const bool value = true;
};
template<> struct IsInteger<unsigned short>     {
    static const bool value = true;
};
template<> struct IsInteger<int>                {
    static const bool value = true;
};
template<> struct IsInteger<unsigned int>       {
    static const bool value = true;
};
template<> struct IsInteger<long>               {
    static const bool value = true;
};
template<> struct IsInteger<unsigned long>      {
    static const bool value = true;
};
template<> struct IsInteger<long long>          {
    static const bool value = true;
};
template<> struct IsInteger<unsigned long long> {
    static const bool value = true;
};

#if !defined(WTF_COMPILER_MSVC) || defined(_NATIVE_WCHAR_T_DEFINED)
template<> struct IsInteger<wchar_t>            {
    static const bool value = true;
};
#endif

COMPILE_ASSERT(IsInteger<bool>::value, WTF_IsInteger_bool_true)
COMPILE_ASSERT(IsInteger<char>::value, WTF_IsInteger_char_true)
COMPILE_ASSERT(IsInteger<signed char>::value, WTF_IsInteger_signed_char_true)
COMPILE_ASSERT(IsInteger<unsigned char>::value, WTF_IsInteger_unsigned_char_true)
COMPILE_ASSERT(IsInteger<short>::value, WTF_IsInteger_short_true)
COMPILE_ASSERT(IsInteger<unsigned short>::value, WTF_IsInteger_unsigned_short_true)
COMPILE_ASSERT(IsInteger<int>::value, WTF_IsInteger_int_true)
COMPILE_ASSERT(IsInteger<unsigned int>::value, WTF_IsInteger_unsigned_int_true)
COMPILE_ASSERT(IsInteger<long>::value, WTF_IsInteger_long_true)
COMPILE_ASSERT(IsInteger<unsigned long>::value, WTF_IsInteger_unsigned_long_true)
COMPILE_ASSERT(IsInteger<long long>::value, WTF_IsInteger_long_long_true)
COMPILE_ASSERT(IsInteger<unsigned long long>::value, WTF_IsInteger_unsigned_long_long_true)

#if !defined(WTF_COMPILER_MSVC) || defined(_NATIVE_WCHAR_T_DEFINED)
COMPILE_ASSERT(IsInteger<wchar_t>::value, WTF_IsInteger_wchar_t_true)
#endif

COMPILE_ASSERT(!IsInteger<char *>::value, WTF_IsInteger_char_pointer_false)
COMPILE_ASSERT(!IsInteger<const char * >::value, WTF_IsInteger_const_char_pointer_false)
COMPILE_ASSERT(!IsInteger<volatile char * >::value, WTF_IsInteger_volatile_char_pointer__false)
COMPILE_ASSERT(!IsInteger<double>::value, WTF_IsInteger_double_false)
COMPILE_ASSERT(!IsInteger<float>::value, WTF_IsInteger_float_false)

template<typename T> struct HashTraits;

template<bool isInteger, typename T> struct GenericHashTraitsBase;

template<typename T> struct GenericHashTraitsBase<false, T> {
    static const bool emptyValueIsZero = false;
    static const bool needsDestruction = true;
};

// default integer traits disallow both 0 and -1 as keys (max value instead of -1 for unsigned)
template<typename T> struct GenericHashTraitsBase<true, T> {
    static const bool emptyValueIsZero = true;
    static const bool needsDestruction = false;
    static void constructDeletedValue(T *slot)
    {
        *slot = static_cast<T>(-1);
    }
    static bool isDeletedValue(T value)
    {
        return value == static_cast<T>(-1);
    }
};

template<typename T> struct GenericHashTraits : GenericHashTraitsBase<IsInteger<T>::value, T> {
    typedef T TraitType;
    static T emptyValue()
    {
        return T();
    }
};

template<typename T> struct HashTraits : GenericHashTraits<T> { };

template<typename T> struct FloatHashTraits : GenericHashTraits<T> {
    static const bool needsDestruction = false;
    static T emptyValue()
    {
        return std::numeric_limits<T>::infinity();
    }
    static void constructDeletedValue(T *slot)
    {
        *slot = -std::numeric_limits<T>::infinity();
    }
    static bool isDeletedValue(T value)
    {
        return value == -std::numeric_limits<T>::infinity();
    }
};

template<> struct HashTraits<float> : FloatHashTraits<float> { };
template<> struct HashTraits<double> : FloatHashTraits<double> { };

template<typename P> struct HashTraits<P *> : GenericHashTraits<P *> {
    static const bool emptyValueIsZero = true;
    static const bool needsDestruction = false;
    static void constructDeletedValue(P **slot)
    {
        *slot = reinterpret_cast<P *>(-1);
    }
    static bool isDeletedValue(P *value)
    {
        return value == reinterpret_cast<P *>(-1);
    }
};

template<typename P> struct HashTraits<RefPtr<P> > : GenericHashTraits<RefPtr<P> > {
    static const bool emptyValueIsZero = true;
    static void constructDeletedValue(RefPtr<P> *slot)
    {
        new(slot) RefPtr<P>(HashTableDeletedValue);
    }
    static bool isDeletedValue(const RefPtr<P> &value)
    {
        return value.isHashTableDeletedValue();
    }
};

// special traits for pairs, helpful for their use in HashMap implementation

template<typename FirstTraitsArg, typename SecondTraitsArg>
struct PairHashTraits : GenericHashTraits<pair<typename FirstTraitsArg::TraitType, typename SecondTraitsArg::TraitType> > {
    typedef FirstTraitsArg FirstTraits;
    typedef SecondTraitsArg SecondTraits;
    typedef pair<typename FirstTraits::TraitType, typename SecondTraits::TraitType> TraitType;

    static const bool emptyValueIsZero = FirstTraits::emptyValueIsZero && SecondTraits::emptyValueIsZero;
    static TraitType emptyValue()
    {
        return make_pair(FirstTraits::emptyValue(), SecondTraits::emptyValue());
    }

    static const bool needsDestruction = FirstTraits::needsDestruction || SecondTraits::needsDestruction;

    static void constructDeletedValue(TraitType *slot)
    {
        FirstTraits::constructDeletedValue(&slot->first);
    }
    static bool isDeletedValue(const TraitType &value)
    {
        return FirstTraits::isDeletedValue(value.first);
    }
};

template<typename First, typename Second>
struct HashTraits<pair<First, Second> > : public PairHashTraits<HashTraits<First>, HashTraits<Second> > { };

} // namespace WTF

using WTF::HashTraits;
using WTF::PairHashTraits;

#endif // WTF_HashTraits_h
